Improvement in lithographic-printing



new $1 1M fitted dffim Letters Patent No. 113,276, dated April 4. 1871.

IMPROVE M ENT IN LlTHOGRAPHlC-PRINTING.

The Schedule referred to in these Letters Patent and making part of the name.

To all whom it may concern Be it known that LOTTO DUBOIS, of Fall River, in the county of Bristol and State of Massacusetts, have invented a new and useful Improvement in the art of Printing Pictures from Lithographic-Stones; and I do hereby'declare that the following specification is a full, complete, and exact description thereof.

My invention resides in a process whereby an effect similar in appearance to that of a pencil-drawing in India-ink or colors, can be given to lithographic prints, and is accomplished by the'following means- A stone, having, been prepared in the usual and commonly-practiced way in the lithographers art for giving impression, instead of inking the same with the opaque ink, usually employed when single impressions V are to be taken, I make use of a transparent ink, made from the common opaque inks, of any preferred color diluted with lithographers varnish, produced from boiled linseed oil; or I make such transparent ink from magnesia mixed with linseed-oil, varnish, and common ink.

No particular proportions are necessary to be observed, the object being to obtain a transparent ink, which, when printed, will give a faint impression;

Any person skilled in the art of lithographic-printing will readily know how to prepare such inks, it being only necessary to'dilute the opaque inks used to print single impressions.

With a transparent ink of the characters described I print an impression; I then ink the stone a second time with the same kind of ink'and reprint the same picture with another impression, and repeat the operation of reprinting, say from five to ten times, until the successive impressions have, by the thickness ofthe overlaid ink-coatings, been brought up in color to the strength. required for the picture.

The result of these reprintings of the same sheet is to dissipate that harshness of expression which is observable in all single impressions taken with opaqueinks, and the picture; if printed in black, has the soft-' ness of an India-ink drawing; the several coatings oi transparent ink blending together and obscuring the coarse lines of the stone.- The same mellow client will characterize a picture printed as described with inks of any other color than black.

What I claim as my invention, and desire to secure by Letters Patent, is-

The improvement in the art or process of printing pictures from lithographic-stones, substantially ash ereinbefore described, for the purposes set forth.

OTTO DUBOIS.

Witnesses: 1

PETER F. HUGHES, A. J. Gusmne. 

